Least x=a(n) such that product of common prime-divisors [without multiplicity] of sigma(x) and phi(x) equals n; or 0 if n is not a squarefree number or if no such x exists. Among indices n only squarefree numbers arise because multiplicity of prime factors is ignored.
A082057
Least x=a(n) such that product of common prime-divisors [without multiplicity] of sigma(x) and phi(x) equals n; or 0 if n is not a squarefree number or if no such x exists. Among indices n only squarefree numbers arise because multiplicity of prime factors is ignored.
Terms
- a(0) =1a(1) =3a(2) =18a(3) =0a(4) =200a(5) =14a(6) =3364a(7) =0a(8) =0a(9) =88a(10) =9801a(11) =0a(12) =25281a(13) =116a(14) =1800a(15) =0a(16) =36992a(17) =0a(18) =4414201a(19) =0a(20) =196a(21) =2881a(22) =541696a(23) =0a(24) =0a(25) =711a(26) =0a(27) =0a(28) =98942809a(29) =209
External references
- oeis: A082057